Java in Mac OS X 10.4 through 10.4.11 allows remote attackers to bypass Keychain access controls and add or delete arbitrary Keychain items via a crafted Java applet.
http://www.vupen.com/english/advisories/2007/4224
http://secunia.com/advisories/28115
http://lists.apple.com/archives/Security-announce/2007/Dec/msg00001.html